The invention includes embodiments that relate to a cure system and an adhesive system. The invention includes embodiments that relate to an electronic device made using the cure system and adhesive system.
Semiconductor chips may be mounted to a substrate in an electronic device. The mounting may not be perfect and air-filled gaps may result between a surface of the chip and a surface of the mounting substrate. Because the air gaps may be undesirable, an underfill resin may be used to fill in the gaps. Underfill material may be used to improve reliability of the device. Further, the use of an underfill material may improve a fatigue life of solder bumps in an assembly.
To address shortcomings associated with traditional capillary underfill resins, a No-Flow Underfill (NFU) material was developed. No-Flow Underfill may include a curable resin, such as an epoxy resin, and may be unfilled, or filled with nano-size filler. The resin filler may be functionalized colloidal silica. The higher the filler content in the resin, the closer may be a match of the coefficient of thermal expansion (CTE) of the cured resin relative to a semiconductor chip. Unfortunately, for reasons of processability and the like, filler loadings of more than about 50 weight percent in the uncured resin may be problematic. To exacerbate the situation, after the addition of a curing agent, the final filler loading may be below 30 weight percent of the total composition. A typical CTE of a cured no-flow underfill epoxy resin with filler loading below 30 weight percent may be above 50 ppm/° C.
It may be desirable to have an underfill material having one or more of a coefficient of thermal expansion of less than 50 ppm/° C., a filler loading of greater than 30 weight percent, an acceptable level of processability, transparency, or a desirably high glass transition temperature (Tg). It may be desirable to have a process for making and/or using an underfill material system having improved or different properties than are currently available. It may be desirable to have an apparatus or article employing a no-flow underfill material system having improved or different properties than are currently available.